Method and apparatus for folding trailing flaps



L. E. LA BOMBARD 2,883,917

April 28, 1959 METHOD AND APPARATUS FOR FOLDING TRAILING FLAPS Filed Jan. 13, 1956 4 Sheets-Sheet l v 'INVENTOR. LEONE. LABOMBARD BY HM Em:

ATTORNEYS L. E. LA BOMBARD April 28, 1959 METHOD AND APPARATUS FOR FOLDING TRAILING FLAPS Fi led Jan. 13, 1956 4 Sheets-Sheet .2

R m WM MA m Z 0 T w A E W W E L P April 28, 1959 E, LA BOMBARD 2,883,917

METHOD AND APPARATUS FOR FOLDING TRAILING FLAPS Filed Jan. 15, 1956 4 Sheets- -Sheet 3 2 I5 I 211914;- in M 201 1' F INVENTOK.

LEONE LABOMBARD ATTORNEYS April 28, 1959 E. LA BOMBARD 2,883,917

METHOD AND APPARATUS FOR FOLDING TRAILING FLAPS I Filed Jan. 15, 1956 4 Sheets-Sheet 4 INVENTOR. LEONE. LABOMBARD M//////////I/// BY.

w-FZM Fig.1]. 3 ATTORNEYS United States Patent'()" METHOD AND APPARATUS FOR FOLDING TRAILING FLAPS Leon E. La Bombard, Nashua, N.H.

Application January 13, 1956, Serial No. 558,966

6 Claims. (Cl. 93-49) This invention relates to an improved folding machine for use in making boxes of the knock-down, inwardly collapsed type well known in the trade.

This application is a continuation in part of my application Serial No. 223,383, filed April 27, 1951 (now Letters Patent 2,764,918, granted October 2, 1956), the said application being directed to the leading flap folding means and this application being directed to the trailing flap folding means of the invention.

The principal object of my invention is to provide improved means for infolding the trailing articulated flaps of the blanks from which such boxes are formed while the blanks travel in a straight line path through the machine.

Another object of my invention is to provide such improved infolding mechanism in a compact and lightweight form whereby my folding machine may be easily moved about a box factory and up against various other box making machines which perform additional operations on the box.

Another object of my invention is to eliminate certain hold-down elements, used in prior devices to assure the infolding of the flaps on their line of articulation, by providing an infolding finger of such shape, material and angle of operation as to make such hold-down elements unnecessary with a resulting simplification of the operation.

A further object of my invention is the provision of means for temporarily fixing each blank in a position of rest in the machine while the infolding of the trailing flaps takes place thus eliminating infolding mechanism which travels along with the blank, as in prior devices.

Still another object of my device is to provide compactly arranged automatic infolding mechanism made up of easily movable and adjustable parts whereby blanks of a variety of sizes and dimensions may be folded in the machine, and capable of operation at high speed without malfunction.

From a method point of view, I have devised a new flap folding method, which improves over previous methods in that my hooked folding finger contacts a blank flap when the adjacent portions of the blank are in flattened condition, without the rigidity provided by previous blank folds and without hold-down mechanism located opposite, or proximate, the point of folding pressure thereon. My new method provides for progressively applied pressure at the edge of an articulated flap, already weakened at the line of articulation by a crease and preferably a score, during at least one half of the infolding of the flap. It also provides for the main body of the blank to be supported from buckling below theipaper line in a direction opposite to the pull of my hooked folding fingers and for the main body of the blank to be held from sliding along the paper line in the direction of pull of the hooked folding fingers.

By my new method, therefore, the pressure of the hooked folding fingers on the edge of an articulated flap will cause a'buckle in the blank above the paper line at 2,883,917 Patented Apr. 28, 1959 the line of flap articulation and thereby force the portion of the blank to which the flap is articulated, to lie flat during the folding operation. Continued pressure and motion of the hooked finger in the direction of infolding holds the buckled blank against its support until the flap fold takes place at the weakest point, the creased and scored line or articulation.

My new method of folding a flap, on an already weakened line of articulation can be accomplished with a single hooked element to make a complete infold and does not necessarily require contact with the undersurface of the flap as in prior methods and machines. Folding methods including the step of pushing against the undersurface of an articulated flap require mechanism to prevent the entire blank from lifting during the first half of the infold and such mechanism must then be moved out of the way of completion of the infold, all of which prevents high speed operation.

Other objects of my invention will appear from the following description and drawings and in the claims hereto annexed.

In the drawings:

Fig. 1 is a diagrammatic side elevation of my improved folding machine on line 1-1 of Fig. 2.

Fig. 2 is a diagrammatic plan view of the device shown in Fig. 1.

Fig. 2A is an enlarged plan view of the preferred type of blank used in my machine.

Figs. 3 to 7 are enlarged fragmentary side elevations of the trailing flap infolding mechanism of my device in various stages of operation while the blank is clamped in a position of rest on the paper line.

Fig. 8 is an end elevation on line 88 of Fig. 5 showing my hold-down and folder bars and showing one of the rotatable supports of the invention broken away.

Fig. 9 is an enlarged side elevation of the preferred form of my new folding finger.

Fig. 10 is a view similar to Fig. 9 of a modification and Fig. 11 is a view similar to Fig. 9 of still another modification.

As shown in the drawings the knock-down inwardly collapsed box for which my folding machine is especially suitable is preferably formed from a fiat blank A of bendable sheet material such as fibre board, having cuts or slits therein at 28, 29, 30 and 31, underscored crease or fold lines therein at 20, 21, 22 and 23 and diagonal underscored crease or fold lines therein at 24, 25, 26 v and 27. The cuts and creases described above divide the fiat blank A into a bottom or main body panel 1, side wall panels or flaps 2 and 3, end wall panels, or flaps, 4 and 5, sealing flaps 6, 7, 8 and 9 foldably connected to end wall panels 4 and 5 and triangular tabs 10, 11, 12 and 13 formed in, and foldably connected to side wall panels 2 and 3.

. In my folding machine a blank such as A, travels therethrough, along the paper line P, with the underscored crease or fold lines 20 and 22 transverse to the path of the blank. During its passage through the machine, blank A is folded into the form shown at B wherein sealing flaps 6, 7 and 8, 9 are infolded toward each other fiatwise against end panels 4 and 5, side wall panels, or flaps, '2 and 3 are infolded toward each other and flatwise against bottom panel 1 and triangular tabs 10, 11, 12 and 13 are back folded on the diagonal crease lines 24, 25, 26 and 27 in the opposite direction from that of side wall flaps 2 and 3.

I call side wall panel, or flap 3 and sealing flaps 7 and 9 the trailing flaps of blank A and I call side wall panel or flap 2 and sealing flaps 8 and 6 the leading flaps of blank A as convenient terms to describe the position of the same in passing along the paper line of my machine. As shown in Figs. 1 and 2, I provide a frame C having side frame pieces 51 and 52, end frame pieces 53 and 54, four legs such as 55 and rollers on each leg such as 56. Blank feeding mechanism G is located at one end of the machine, blank glueing mechanism K is located at the opposite end thereof and intermediate of the ends are located my trailing flap infolding mechanism H and my leading flap infolding mechanism J.

A first conveyor D, including a pair of endless belts or chains 101 and 102, having spaced upstanding abutments 106 and supported on pulleys such as 103, 104 and 105 is positioned to receive blanks A from feeding mechanism G, convey the blanks along the paper line P and release the same at a position of rest on paper line P at a clamping mechanism F.

A second conveyor E, including a pair of endless belts or chains 151, 152, each chain having a spaced series of upstanding abutments such as 153, 153, and supported on pulleys such as 154, 155 and 156 is synchronized to pick up each blank A as it is released from clamping mechanism F, carry the blank along the paper line P and deliver the blank to the glueing mechanism K.

Feeding mechanism G, includes a chute 251, holding a stack 252 of blanks, such as A each positioned so that it will travel through the feeding mechanism, and onto paper line P, with its lines of articulation 20 and 22 transverse to the paper line and to the path of travel of the blanks. Flaps 2, 6 and 8 thus become the leading flaps and flaps 3, 7 and 9 become the trailing flaps. A feed roll 253 is provided, together with a suitable friction roll 254, all in a well known manner, and arranged to deliver a succession of blanks such as A, at spaced intervals to conveyor D.

I find it useful to provide tab breaking mechanism L comprising a rotating member 501 with radially projecting elements 502 each synchronized and positioned to contact a triangular tab such as 10, 11, 12 and 13 of blank A and to give a preliminary articulation thereto on the diagonal fold lines 24, 25, 26 and 27. Subsequent folding of the tabs is thus made easier particularly when the sheet material used in blank A is not easily bendable.

I provide a pair of hold-down and folder bars M and N extending longitudinally of the paper line and slightly above the same in order that each blank A may be carried along the paper line P with its lower surface supported on the second conveyor E and its upper surface in contact with the bars M and N. Between feeding mechanism G and clamping mechanism F I also provide longitudinal guides 700 and 702 above paper line P and above conveyor D, together with a centrally located longitudinal guide or support 701 which extends substantially the entire length of the machine, below the paper line P to support the centre of the blanks A and to prevent their buckling downwardly during the folding operation.

The outer and lower longitudinal edge 604 of a holddown and folder bar, such as M, as shown in Fig. 8, is longitudinally aligned to contact the upper surface of each blank at one of the opposite sides of the bottom or main body panel 1, just inside of a longitudinal line of articulation such as 23. The inner face 608 of each holddown and folder bar, such as M, is normally at an angle of about 30 to the paper line for example along holddown zones 601, 602 and 603 shown in Fig. 2.

Additional hold-down bars such as 620, 621 may be provided above the end flaps 4 and and above flaps 2 and 3 in zones 602 and 603. The end flaps are supported from below by the conveyor E and may also be supported from below by longitudinal support guides 622 and 623.

Along none 605, of a bar M or N, where the infolding of the trailing flaps takes place and along zone 606 where the infolding of the leading flaps takes place the angle of the inner surface 608 of the bars gradually increases to 45 and then decreases again to 30 as indicated in Fig. 8.

Clamping mechanism vF of my device as shown in Fig. 4 comprises a bar or plate 201, located below the paper line, and below the hold-down and folder bars M and N pivotally mounted at one end 236 and having its opposite end 217 vertically movable by rods 202, the rods being slidable in sleeve members 203 in frame C. A cam 204, mounted on shaft 205, is provided with a circumferential cam track 206, recessed at 207, and in contact with a cam follower 208 pivotally mounted at 209.

Cam follower 208 is provided with a tension spring 216 (Fig. 7) to keep it in contact with cam track 206, and is connected to rods 202 by an arm 209 extending across the machine to enable transverse positioning of the clamp F and hold-down bars M and N without moving the cam mechanism. Clamp bar 201 is caused to lift the undersurface of a blank A from conveyor E and clamp the blank tightly against the undersurface 604, of a bar such as M, while cam follower 208 is engaged in recess 207 of cam 204 and is caused to release the blank back onto conveyor E while the follower 208 is engaged by the surface 206 of 204.

The trailing flap infolding or overfolding mechanism H of my machine comprises one or more rotatable supports 301, revolving on a shaft 302 in the direction shown by the arrows whereby the portion of the circumference adjacent the paper line P travels in the same direction as the blanks A on the paper line and in close proximity thereto. Each rotatable support 301, is provided with one or more circumferential flap recesses such as 303, 304 and is also provided With a stationary cam member 305, kept from revolving with shaft 302 by an integral arm 306, having a shaft recess 307, for a shaft 308 by which it is retained and adjusted on frame C.

Associated with each flap recess such as 303 is an elongated folding finger 309 having a hook 310 at its free end and pivotally mounted on a pivot 311 in rotatable support 301 to permit vertical oscillation in a cavity 312 formed between the side walls of support 301. A link 313 is pivoted at 314 intermediate of finger 309 and the other end of the link at roller cam follower 315 is pivotally retained in the endless cam track 316 of cam member 305, there being radial slots 327 in support 301 to give access to cam track 316. An arm 323 is pivotably connected at the roller cam follower 315 and its opposite end is pivotally connected to support 301 at 324. As best shown in Fig. 8 each support 301 includes a hub 325 connecting the same to rotating shaft 302 the hub being rotatable in suitable hearings in stationary arm 306 and having a collar 326 on the opposite side of the arm 306. As each rotatable support 301 revolves in synchronization with the travel of the conveyors D and E and with cam 204 of clamping mechanism F, each elongated finger 309 arrives at the paper line P projecting circumferentially from 301 at a low angle of elevation to the piper line so that it is nearly parallel to and flush with the surface of a blank A. As shown in Fig. 3, finger 309 extends in a rearward direction over the forward end of the first conveyor D and the downwardly depending hook 310 extends into the paper line sufiiciently to hook over the trailing edge of a trailing articulated flap such as 3 of a blank A.

As rotatable support 301 continues to revolve in the direction of the arrows, hook 310 of finger 309 pulls the blank A, by the trailing edges 40 of a flap such as 3, forwardly out of the path of the spaced upstanding abutments 106 of conveyor D until the adjacent line of articulation such as 22 is positioned in the path of the spaced upstanding abutments 1.53 of conveyor E. When the blank has thus been pulled by finger 309 into the correct position for infolding of the trailing flaps, cam 204 operates to clamp the blank in a temporary position of rest against the under surface of holddown and folder bars M and N as shown in Fig. 4.

Abutments 153 on conveyor E are so spaced and timed that the distance therebetween provides a slight time interval before an abutment reaches the trailing edge of a blank formed by crease line 22 and during whichtime interval the infolding of the trailing flaps takes place.

The further rotaton of support 301 causes cam track 316, arm 323 and link 313 to pivot finger 309 inwardly into cavity 312, the hook 310, and the edge 40 of the trailing flap 3 of blank A grasped thereby rising slightly to the position shown in Fig. 4. This liftin of flap 3 is opposed by the resistance of the 45 inner face zone 605 of bars M and N which urge the triangular tabs such as 12 and 13 backwardly on their fold lines 26 and 27. As indicated in Fig. 4, the pressure of hook 310 on trailing edge 40 of a trailing flap 3 first causes the blank A to buckle or bow and then causes the flap to fold upwardly on the weakened line of articulation 22, the pressure also forcing the blank A to remain substantially flat on the paper line P. As shown in Fig. 5 support 301 has rotated sufiiciently to cause finger 309 to assume a greater angle of elevation to paper line P and to be well within the cavity 312 of 301 thereby bringing the flap such as 3 of A into the flap recess 303 in an upstanding position.

In Fig. 6 the support 301 is shown in a position of rotation wherein the finger 309 and hook 310 release the flap 3 while the positive pushing element of support 301, comprising the opposite inner face 318 of recess 303, preferably provided with a roller 319, is about to contact the undersurface of the flap at 30.

In Fig. 7 the infolding of flap 3 is shown as completed by the pusher element 318, by its roller 319, while finger 309 is again being moved into folding position by arm 323 operated by cam track 316. As shown in Fig. 7, the clamping mechanism F, with cam follower 208 now engaged on surface 206 has released the blank to the conveyor E and an abutment 153 is about to carry the blank with its trailing flaps infolded through the remainder of the machine. As indicated in Figs. 5, 6 and 8 the triangular tabs 12 and 13 of a flap such as 3 are backfolded by the inner faces of bars M and N as flap 3 is infolded and are held in this position by contact with the 30 inner faces of bars M and N in zone 602.

An abutment such as 153 of conveyor E contacts the trailing edge of each blank A after its trailing flaps have been infolded and its triangular tabs backfolded by infolding mechanism H and bars M and N and moves the same along paper line P to the leading flap infolding mechanism J of my folding machine.

The leading flap infolding mechanism I of my invention is described in detail in my said application Serial No. 223,383 of April 27, 1951. In general, it comprises a resilient hooked finger 353 for engaging the leading edge of the leading flaps of each successive blank passing thereunder, pivoting upwardly therewith and releasing the flap to a downfolding member 370. The leading flap folding finger is timed to oscillate upwardly out of the Way of a folded trailing flap passing thereunder and then return to leading flap engaging position.

In passing along the paper line P on conveyor E and in zone 603 of the bars M and N the blank A has assumed the form shown at B and is ready for the glueing operation. I provide suitable glueing mechanism K, having glue pots 401 and glue rolls 402 arranged to transfer a coating of glue 403 to a triangular portion of infolding sealing flaps 6, 7, 8 and 9 corresponding to the area of triangular tabs 10, 11, 12 and 13. The infolding of end flaps 4 and 5 and their infolded sealing flaps to overlie the bottom panel 1 and adhere to the triangular tabs is preferably performed on another machine and may be done in any well known manner.

As shown in Fig. 9, I prefer to make my elongated folding fingers such as 309 and 353 of resilient metal in order that they will have a yielding engagement with the edges 40 and 50 of the leading and trailing flaps. Resilient fingers tend to bow slightly as they exert a pulling force on the edge of the flap and a downward force on the blank itself and assist in causing the blank to bow slightly until the flap commences to fold on its weakened line of articulation. In any case, by applying a pulling force to the edge of the flaps my infolding fingers cause the flaps to articulate upwardly without any complicated mechanism to engage and press down the upper surface of the blank near the line upon which articulation is desired.

While the pulling elements of my infolding mechanism are preferably yieldable as stated above, the pushing elements such as 318 and 370 are positive in operation to assure the completion of the infolding of each flap and the backfolding of its triangular tabs, if any, thereon.

It will be apparent that all of the mechanism of my folding machine is transversely adjustable to accommodate blanks of various sizes and dimensions. I may provide one infolding mechanism H and J for each articulated flap but as shown in Fig. 8, when a flap such as 2 or 3 is of substantial length I prefer to provide two or more of the same, two of which are each located proximate a hold-down bar such as M and N.

As shown in Fig. 9 I prefer to provide a curved hook, such as 310 arranged to engage the edge of a flap on its inner curved surface 340 and having its tip 341 arranged to engage the centre of the undersurface of a flap such as 3 as it is raised to assist in the support thereof.

However, a curved hook such as 700, shown in Fig. 10

may be used on a finger 702, the tip 704 thereof being arranged to contact the upper central portion of an upraised flap rather than the central portion or, as shown in Fig. 11, I may use a hook 703 at right angles to a finger 705 with satisfactory results.

It is obvious that my machine and method can be used to infold box blanks of types other than that shown at A, wherein straight line infolding of leading and trailing flaps is desired at high speed and Without complicated mechanism.

I claim:

1. Mechanism for infolding a trailing articulated flap of a flat box blank, while the main body thereof is stationary and held down on the paper line of a folding machine, said mechanism comprising a circular support, rotating above, and on an axis transverse to said paper line, and having a flap recess in the circumference thereof; an elongated, yielding finger, pivotally mounted on said support, said finger extending above and substantially parallel to said blank and having a hook positioned to engage the trailing edge of said flap at the paper line; cam means maintaining the hook of said hooked finger on a level proximate the level of said paper line while the finger is carried forwardly and upwardly in a curved path on said rotating support, until said finger releases the flap engaged and raised by said hook into the fiap recess of said rotating support; and pushing means, on the trailing wall of said recess, positioned to contact said raised flap and complete the forward infolding thereof as said support continues rotating.

2. Mechanism according to claim 1 wherein said hook is curved back upon itself, and arranged to first engage the edge of a flap on the curved inner face of said hook and subsequently to engage the under face of the flap with the tip of said hook approximately at the transverse centre line of said flap.

3. A device for use in the infolding of a flap articulated to a flat portion of a fiat box blank by a weakened line of articulation, said infolding being in the plane of the path of said box blank through a folding machine, said device comprising an elongated hooked finger pivotally mounted above said path in position to hook onto a free edge of said articulated flap and means for varying the direction of the pressure of said hooked finger on the edge of said flap to cause an infold to take place at said weakened line of articulation, said pressure direction varying means including a resilient shank on said finger and mechanism for advancing said finger in the direction of fold while oscillating said finger on its pivotal mounting.

4. The method of infolding the articulated trailing flaps of a flat box blank as the box blank is supported on the paper line of a folding machine, which comprises feeding the box blank with the lines of articulation of said flaps transverse to said paper line, to a position of rest on said paper line; clamping said blank in said position of rest with the area thereof adjacent the trailing line of articulation free to bow upwardly; completely infolding the trailing articulated flaps of said blanks, While clamped in said position of rest by first bowing the blanks and flaps to upfold the flaps and then downfolding the flaps; releasing said blank, from said clamped position to continue traveling along said paper line and then infolding the leading articulated flaps, while said blank is traveling along said paper line, with the area thereof adjacent the leading line of articulation free to bow upwardly, by first bowing the blank and flaps to upfold the flaps and then downfolding the flaps.

5. The method or" infolding the articulated trailing flaps of a fiat box blank, traveling along the paper line of a folding machine with the line of articulation of said flaps, transverse to the paper line which comprises the steps of clamping said blank in a position of rest on said paper line; pulling on the trailing edges of said articulated flaps, with a yielding pressure first exerted at a low forward angle of elevation thereto and continuing to pull at a gradually increasing angle of elevation thereto while said flap bows and then bends on its line of articulation until said 8 fiap assumes an upstanding position; pushing on said upstanding fiap to complete the infolding thereof and then releasing said blank from said clamped position of rest to continue traveling on said paper line with its trailing flaps infolded.

6. The method of infolding an articulated flap of a fiat box blank which comprises the steps of holding a box blank against movement in a horizontal plane while supporting the undersurface of the blank against downward movement; then pulling the flap of said blank to be folded upwardly and forwardly toward the centre of the blank by its outer peripheral edge while simultaneously applying resilient downward pressure on said edge to cause said blank to bow and said flap to upfold on its line of articulation, then exerting a further pull on the undersurface of said flap until the flap is in a substantially upstanding position; then exerting a pushing on the undersurface of said flap forwardly toward the centre of the blank and downwardly until it overlies said blank and then releasing said blank from its horizontally immovable position.

References Cited in the file of this patent UNITED STATES PATENTS 1,370,654 La Bombard Mar. 8, 1921 1,505,178 Wade Aug. 19, 1924 2,112,121 Sidebotham Mar. 22, 1938 2,197,089 Anderson Apr. 16, 1940 2,336,507 Shields Dec. 14, 1943 

